A laser driven electron x-ray source (LEXS) emitting tungsten Lα lines has been built based on a high repetition rate, terawatt laser system. The Lα characteristic lines overlap with the absorption edge of Ni near 8333 eV. Using this x-ray source, the x-ray absorption spectra near the absorption edge of different Ni compounds have been measured. We term this new method “ultrafast selected energ...

Recent studies of Quasi-Stellar Objects (QSOs) with ROSAT suggest the existence of a significant population of Soft X-ray Weak QSOs (SXW QSOs) where the soft X-ray flux is ∼ 10–30 times smaller than in typical QSOs. Why are these QSOs soft X-ray weak, and what is their relationship to Broad Absorption Line QSOs (BAL QSOs) and X-ray warm absorber QSOs? As a first step in a systematic study of th...

X-ray emission spectra recorded in the off-resonant regime carry information on the density of unoccupied states. It is known that by employing the Kramers-Heisenberg formalism, the high energy resolution off-resonant spectroscopy (HEROS) is equivalent to the x-ray absorption spectroscopy (XAS) technique and provides the same electronic state information. Moreover, in the present Letter we demo...

Direct industrial application of x-ray absorption spectroscopy is demonstrated by research in catalysis (CO/H2 and naphtha reforming) and corrosion protection.

Owing to its element specific and short-range nature, core-level X-ray absorption spectroscopy (XAS) is now routinely used to elucidate the local structural, vibrational, and other physical properties of complex, aperiodic materials. XAS encompasses both extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge spectra (XANES) [1, 2], where the terms refer, respectively, t...

The breaking of time-reversal symmetry (TRS) in topological insulators is a prerequisite for unlocking their exotic properties and for observing the quantum anomalous Hall effect (QAHE). The incorporation of dopants which exhibit magnetic long-range order is the most promising approach for TRS-breaking. REBiTe3, wherein 50% of the Bi is substitutionally replaced by a RE atom (RE = Gd, Dy, and H...

We consider fundamental structures in x-ray absorption spectra over a wide energy range. We formulate the elastic scattering in addition to the photoelectric absorption in recently reported photon interference x-ray absorption fine structure (pXAFS). The simulations show excellent agreement with experimental x-ray absorption spectra for platinum and tungsten powders far above and below the L ab...

We present the results from simultaneous observations of the Narrow-Line Seyfert 1 galaxy NGC 4051 with the Chandra High Energy Transmission Grating Spectrometer and the HST Space Telescope Imaging Spectrograph. The X-ray grating spectrum reveals absorption and emission lines from hydrogen-like and helium-like ions of O, Ne, Mg and Si. We resolve two distinct X-ray absorption systems: a high-ve...

We briefly describe some recent observational results, mainly at X-ray wavelengths, on the winds of luminous active galactic nuclei (AGNs). These winds likely play a significant role in galaxy feedback. Topics covered include (1) Relations between X-ray and UV absorption in Broad Absorption Line (BAL) and mini-BAL quasars; (2) X-ray absorption in radio-loud BAL quasars; and (3) Evidence for rel...